discuz 想在门户首页自定SQL读取数据库信息，该怎么操作？

<?php$query = DB::query("SELECT * FROM ".DB::table('common_advertisement').";");		while($rs = DB::fetch($query)) {			$code=$rs['code'];		}?>

<?php$query = DB::query("SELECT * FROM ".DB::table('common_advertisement') );		while($rs = DB::fetch($query)) {			$code=$rs['code'];		}?>

if(!class_exists('DB')){	echo '不存在';}

require_once './source/class/class_core.php';//根目录下C::app()->init();

<?php exit; ?><!--{subtemplate common/header}-->...<!--{subtemplate common/footer}--> 

if(!class_exists('DB')){    echo '不存在';}

<?php exit; ?><!--{subtemplate common/header}--><?php$query = DB::query("SELECT * FROM ".DB::table('common_advertisement') );        while($rs = DB::fetch($query)) {            $code=$rs['code'];        }?><!--{subtemplate common/footer}-->